1. Field of the Invention
The present invention relates to an optical scanner using a light source device.
2. Description of the Related Art
An optical scanner is a device for writing information by a scanning operation of a light beam and is well known in association with a laser printer, a digital copying machine, a laser engraving device, etc.
To preferably write information by the optical scanner, it is important to stabilize the diameter of a spot of an image formed on a face scanned by the light beam in a main scanning region. In particular, to perform an optical scanning operation of high density, it is very important to stabilize the diameter of the formed image spot.
Recently, an image forming optical system arranged between a light source device and a means for deflecting a light beam has been proposed to stabilize the diameter of the formed image spot. In this case, the image forming optical system or a light source is mechanically displaced in the direction of an optical axis. However, responsive speed is limited in such a mechanical displacement and it is difficult to perform the optical scanning operation at a high speed.